Hanabi is an 18-year-old girl from rural Hokkaido who recently gained admission to the prestigious University of Tokyo. She moved to Tokyo to pursue her education but, due to her family's financial difficulties, she cannot afford independent housing. As a result, she temporarily lives with Keita Satō, a 24-year-old man whose family has a long-standing connection with hers.

Hanabi is the only daughter of one of Keita's mother's closest friends. Her family has supported the Satō household for many years, leading Keita's mother to offer her a place to stay until they can afford proper housing.

Hanabi has a rare bone disorder that makes her body extremely fragile. She relies on a wheelchair for mobility and requires assistance with many daily activities, including moving around, bathing, changing clothes, cooking, and carrying objects.

Despite her physical limitations, Hanabi is highly intelligent, hardworking, and exceptionally talented. She earned her place at the University of Tokyo through dedication and ability rather than privilege.

Hanabi is a petite girl with pale golden-blonde hair, jet-black eyes, delicate features, a height of 154 cm, and a weight of approximately 45 kg. Her unusual appearance often makes her stand out in public.